Leaching and extraction of metals from their ores.



UNrrnn STATES PATIENT OFFICE.

CARL HOEPFNER, OF FRANKFORT-ON'1HE-MAIN, GERMANY; HENRY ORTII, JR,ADMINISTRATOR OF SAID HOEPFNER, DECEASED.

LEACHING AND EXTRACTION OF METALS FROM THEIR ORES.

SPECIFIGATION forming part of Letters Patent No. 704,639, dated July 15,1902.

Application filed September 27, 1899.

T aZZ whom it may concern:

Be it known that I, OARL I-IOEPFNER, a subject of the Emperor ofGermany, residing at Frankfort-on-the-ll/lain, Germany, have inventedcertain new and useful Improvements in the Leaching and Extraction ofMetals from Their Ores; and I do hereby declare the following to be afull, clear, and exact description of the invention, such as will enableothro ers skilled in the art to which it appertains to make and use thesame.

This invention relates to extraction of metals from their ores, niattes,or other materials, and is designed to be especially used for theextraction of copper, lead, and silver from complex argentiferous orcupriferous sulfids or ores by means of cupric chlorid and to overcomemany difficulties arising in the practical operation of the processdescribed in Letters Patent granted to me October 24, 1893, and

numbered 507,130, wherein I use a cupricchlorid solution saturated withchlorid of alkali or alkaline earths for leaching sulfur ores of copper,silver, lead, zinc, 850., whereby 2 5 these metals are converted intotheir respective chlorids, the cupric chlorid is converted into cuprouschlorid, and such metallic impurities, as cobalt, antimony, bismuth,arsenic, iron, &c., as are very often found in such 0 ores areeliminated by precipitation to obtain a practically pure chlorid or suchcontaining only silver. This cuprous-chlorid solution is thenelectrolyzed in a suitable apparatus, wherein the copper cathodes andcarbon an- 3, 5 odes are in separate compartments separated by asuitable diaphragm, as described in the aforesaid patent. Throughoutthis description I mention alkaline-metal chlorids and use the term asembracing both the metals of the alkalies and of the alkaline earths.Many years experience with this process has revealed certain drawbackswhich, if obviated, greatly add to its commercial success, especiallywhen low-grade ores are treated, and which drawbacks are, first,considerable loss of chlorids in the waste residues; second, difficultyin securing for the cathodes a solution sufficiently free from cupricchlorid, (ouc1,, which decreases the output and is liable to deterioratethe quality of the product; third, it requires too long a time to removethe iron Serial No. 731,852. (No specimens.)

from the solutions by the action of air thereon, which will require toomany tanks under supervision and necessarily increase the space requiredfor the plant; fourth, this implies also a loss of heat in the solutionswhen separated from the ores and renders the automaticalcontinuous-counter-current system of heating and lixiviating useless;fifth, in such solutions the solubility of cupric chlorid is verylimited, especially when iron, zinc, and othermetals are present,so thatthe production of strong 011 01 solutions becomes difficult; sixth,solutions being often overconcentrated precipitate their contents on aslight fall of temperature, thereby producing sediments which greatlydeteriorate the copper products and that cover the anodes, and thusoften double the required voltage and at the same time produce freechlorin, which quickly destroys the diaphragms. Experience has shownthat the peculiar nature of cuprous-chlorid solutions makes it verydifficult, almost iinpossible, to obtain a homogeneous solid copperexcept in the absence of cupric chlorid and also of iron. Now to obviatethese difficulties I refrain from using cupric-chlorid solutionssaturated with chlorid of alkalies or alkaline earths; but I do usethelatter in proportions of three-fourths to one-fourth saturating quan-8o tity. This gives me the benefit of the following result: First,cupric-chlorid solutions containingless than the saturation quantity ofchlorid of alkali and alkaline-earth metals can be made moreconcentrated in cupric-chlorid; second, when heated to 60 to 100 or moreCelsius they are very active solvents of copper, sulfid of copper,silver, and other associated metals with the formation of cuprouschlorid; third, that when hot are very good 0 solvents for cuprouschlorid, lead chlorid, and silver chlorid, which are rendered partiallyinsoluble by cooling, a very easy means of separating these salts;fourth, these precipitates after separation and purification can be usedat the cathodes by being added to the cathode solution, therebyproviding a very convenient supply for the said solution; fifth, thesolid OU GI precipitate when oxidized is a very efficient precipitantfor iron; sixth, the zoo mother-liquor containing more or less CuCl canbe used either for a second leaching or for ferred to.

use at the anodes, where its contents of onprous chlorid can becompletely converted into cupric chlorid; seventh, the residues containobviously less chlorids; eighth, the leaching process requires smallertanks and less time because very strong cupric-chlorid solutions can beused and not all of the cupric chlorid need be converted into cuprouschlorid; ninth, there is no longer trouble at the anodes and cathodesdue to overconcentration of the solution; tenth, from solutionscontaining lead the lead is more completely precipitated when cooled.These advantages make it possible to save chlorids, heat, labor, andspace, all of vital importance to the successful commercial operation ofa leaching process, especially when low-grade ores are used.

When applied to complex ores containing zinc, copper, silver, lead,iron, and other associated metals, the process is preferably, but notnecessarily, carried out in two or more steps. The ore is first leachedwith a sufficient quantity of a warm solution of cupric chloridcontaining the stated amount of alkaline-metal chlorid in order todissolve the lead and silver, but of course some iron will also bedissolved, The lead chlorid and some of the silver chlorid thus formedare precipitated by refrigeration and the cuprous chlorid (reduced fromthe cupric chlorid by the action of the liquor on the ores with theconversion of the lead and silver into chlorid) is reconverted intocupric chlorid by free chlorin obtained in any suitable manner butconveniently from the reduction of the lead chlorid previouslyprecipitated or zinc chlorid obtained in a subsequent stage, or I mayeifect the conversion by using the solution as an anode electrolyte in asuitable apparatus.

The troublesome iron is precipitated by oxy chlorid of copper, (Ou C1O,) hereinafter re- The remaining lead may be precipitated by zinc oxidand carbonic acid; but it is preferable to keep this as a separatesolution for extracting the lead from ores. We have now a liquor freefrom lead chlorid and partially free from silver chlorid. Thiscupric-chlorid solution is returned to the ores h0t'(ofa highertemperature than the first solution) in order to dissolve the copperwith some zinc; but Ipreferably use a second solution stronger in cupricchlorid, containing the stated amount of solvent of cuprous chlorid. Thecopper can then be obtained from the solution electrolytically as wellas the zinc; but preferably I convert some of the cuprous chlorid intooxychlorid of copper by blowing air or oxygen into the electrolyte agentfor iron or to enrich solutions poor in copper, so as to make themsuitable for electrolysis.

Having thus described my invention, what I claim as new therein, anddesire to secure by Letters Patent, is-

1. The process of treating ores and metallic compounds containingcopper, which consists in leaching the same with a cupric-chloridsolution containing a solvent of cuprous chlo rid in quantit-yless thanis required for saturation, and electrolyzing the resulting cuprouschlorid solution while mechanically separating the electrode solutions,thereby depositing metal at the cathode and convert- I ing the cuprousinto cupric chlorid, substantially as described,

2. The process of treating ores and metallic compounds containingcopper, which consists in leaching the same with a cupric-chloridsolution containing a solvent of cuprous chlorid in quantity less thanis required for saturation, precipitating from the solution so obtainedcuprous chlorid, and electrolyzing a solution of the latter at thecathodes and the mother-liquor at the anodes while mechanicallyseparating the electrode solutions,there by depositing copper at thecathode and conv consists in leaching the same with a warm or.

hot cupric-chlorid solution containing a solvent of cuprous chlorid inquantity less than is required for saturation, precipitating leadchlorid by refrigeration, converting the cuprous into cupric chlorid bychlorin, and returning the solution hot for further leaching of similarmaterials, substantially as described.

5. The process of treating ores and metallic compounds containing copperandlead, which consists in leaching the same with a warm or hotcupric-chlorid solution containing a solvent of cuprous chlorid inquantity less than is required for saturation, precipitating the leadchlorid formed by refrigeration, reconverting the cuprous into cupricchlorid in the anode compartment of an electrolytic apparatus, andreturning the solution hot for leaching similar materials, substantiallyas described.

6. The process of obtaining copper, which consists in leachinga suitablematerial with a hot cupric-chlorid solution containing a solvent ofcuprous chlorid in quantity less than is required for saturation,electrolyzing the resulting cuprous'chlorid solution while mechanicallyseparating the electrode solutions, whereby metallic copper is depositedand the cuprous chlorid converted into cupric chlorid, and returning thelatter into the cycle of operations, substantially as described.

7. The process of obtaining copper and silver, which consists inleaching a suitable material with a hot cupric-chlorid solutioncontaining a solvent of cuprous chlorid less than is required forsaturation, partially precipitating the cuprous chlorid from theresulting solution by refrigeration, and electrolyzing the remainder ofthe solution to recover the silver and copper while mechanicallyseparating the electrode solutions, substantially as described.

8. The process of obtaining copper, which consists in leaching asuitable material containing these metals and iron with a hotcupricchlorid solution containing a solvent of onprous chlorid inquantity less than is required for saturation, partially precipitatingcu prous chlorid from the resulting solution, oxidizing the latter andusing a sufficient quantity of the resulting productfor precipitatingiron from the solutions and recovering the copper from the remainder,and returning the resulting liquor into the cycle of operations,substantially as described.

9. In the extraction of copper and silver from their orescontainingiron, the step which consists in precipitating cuprouschlorid. from hot solutions thereof, oxidizing the precipitate by meansof air or oxygen and returning sufficient of the resulting product tothe cuprous-chlorid solution under treatment to pre cipitate iron thatmay be present, substantially as set forth.

10. The process of obtaining copper, which consists in leaching asuitable material with a hot cupric-chlorid solution containing asolvent of cuprous chlorid, partially precipitating the cuprous chloridfrom the resulting solution by cooling and electrolyzing the remainderof the solution to recover copper while mechanically separating theelectrode solutions, substantially as described.

11. In the extraction of copper, the step which consists inprecipitating cuprous chlorid from hot solutions thereof by cooling, re-

moving and dissolving the precipitate by a suitable solution, andrecovering the copper from the resulting solution in the cathodecell ofa suitable apparatus also containing an anode-cell and suitable anodesolution, substantially as described.

12. The process of treating ores and metallic compounds, which consistsin leaching the same with a warm cupric-chlorid solution containing asolvent of cuprous chlorid in quantity less than is required forsaturation, precipitating lead and part of the silver chlorid formed byrefrigeration, reconverting the resulting solution into a cupric-chloridsolution, returning the same at a higher degree of temperature to thematerial treated, thereby dissolving copper, precipitating any excess ofiron by an oxygen compound of copper, electrolyzing the solution torecover the copper and zinc, and returning the resulting electrolyteinto the cycle of operations, substantially as described.

13. In the extraction of copper, the step which consists inprecipitating cuprous chlorid from hot solutions thereof byrefrigeration, oxidizing the resulting solution at the anodes, using asolution of the precipitate in the cathode-cell of a suitable apparatusand depositing the copper, substantially as described.

14. The process of extracting metals, which consists in leaching asuitable material containing copper, lead and silver, with a warmcupric-chlorid solution containing a solvent of cuprous chlorid inquantity less than is required for saturation thereby dissolving leadand silver chlorids, precipitating them, reconverting the solution intocupric chlorid, using the same for leaching fresh quantities of ore,leaching the residues with a similar hot solution more concentrated incupric chlorid, thereby dissolving copper and recovering those metalstherefrom, reconverting the resulting solution into cupric chlorid, andreturning the latter into the cycle of operations, substantially asdescribed.

In testimony that I claim the foregoing as myinvention I have signed myname in presence of two subscribing witnesses.

CARL IIOEPFNER.

WVitnesses:

Tnos. I'I. YOUNG, B. W. SoMMERs.

